The studies proposed are addressed to the clarification of the intimate nature of the fluid transport mechanism across corneal endothelium. It is generally accepted that this transport mechanism is directly responsible for the maintenance of normal corneal hydration and transparency. The small (O.5 - 1 mV) electrical potential difference across this monocellular layer, the sizable fluid transport across it (typically 5-6 micron 1/h/cm2) and other electrical characteristics of the endothelium (resistance: 40 omega cm 2; capacitance: 0.4 micron F/cm2, bot obtained from the impedance locus) are being measured and their behavior with changing ambient condtions is being determined. In a model recently developed by us it is proposed that the corneal endothelium transport mechanism is similar to that of kidney proximal tubule; this model is currently being tested.